A consumer health group yesterday accused the Reagan administration of lax enforcement of drug and health laws administered by the Food and Drug Administration and the Occupational Safety and Health Administration.

"An analysis of the most recent enforcement data we have obtained from the FDA and OSHA shows a consistent and severe retrenchment on law enforcement activities at these agencies under the Reagan administration," Public Citizen said.

The group said the FDA took 260 enforcement actions -- drug seizures, prosecutions or injunctions -- in fiscal 1984, compared with a yearly average of 542 such actions from fiscal 1977 to 1980. Under President Reagan, the FDA has averaged 279 actions a year, or 49 percent fewer than during the Carter years.

OSHA has issued no "complete" health standards to protect workers from exposure to toxic substances since Reagan took office, the group said, compared with six health standards issued under Carter.

The number of violations issued by OSHA inspectors also has dropped significantly in the past four years, the group said. Compared with the Carter administration, data from fiscal 1981 through the first half of fiscal 1984 shows that the number of serious violations issued was down 19 percent, so-called willful violations were down 66 percent, and repeat violations were down 58 percent.

Spokesmen for the FDA and OSHA said they had not seen the report and therefore could not comment on it.